<!Doctype html>
<html>
<head>
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
	<meta name="viewport" content="width=device-width, initial-scale=1.0" />
	<title>Ruby 面向对象 | 菜鸟教程</title>

  <meta name='robots' content='max-image-preview:large' />
<link rel='stylesheet' id='classic-theme-styles-css' href='../0/classic-themes.min.css?ver=6.2' type='text/css' media='all' />
<link rel="canonical" href="../ruby/ruby-object-oriented.html" />
<meta name="keywords" content="Ruby 面向对象">
<meta name="description" content="Ruby 面向对象   Ruby 是纯面向对象的语言，Ruby 中的一切都是以对象的形式出现。Ruby 中的每个值都是一个对象，即使是最原始的东西：字符串、数字，甚至连 true 和 false 都是对象。类本身也是一个对象，是 Class 类的一个实例。本章将向您讲解所有与 Ruby 面向对象相关的主要功能。 类用于指定对象的形式，它结合了数据表示法和方法，把数据整理成一个整齐的包。类中的数据和方法被称为类的成员。   Ruby 类定..">
		
	<link rel="shortcut icon" href="https://static.runoob.com/images/favicon.ico">
	<link rel="stylesheet" href="../0/style.css?v=1.170" type="text/css" media="all" />	
	<link rel="stylesheet" href="../0/font-awesome.min.css" media="all" />	
  <!--[if gte IE 9]><!-->
  <script src=""></script>
  <!--<![endif]-->
  <!--[if lt IE 9]>
     <script src=""></script>
     <script src=""></script>
  <![endif]-->
  <link rel="apple-touch-icon" href="https://static.runoob.com/images/icon/mobile-icon.png"/>
  <meta name="apple-mobile-web-app-title" content="菜鸟教程">
</head>
<body>

<!--  头部 -->
<div class="container logo-search">

  <div class="col search row-search-mobile">
    <form action="index.php">
      <input class="placeholder" placeholder="搜索……" name="s" autocomplete="off">
      
    </form>
  </div>

  <div class="row">
    <div class="col logo">
      <h1><a href="../">菜鸟教程 -- 学的不仅是技术，更是梦想！</a></h1>
    </div>
        <div class="col right-list"> 
    <button class="btn btn-responsive-nav btn-inverse" data-toggle="collapse" data-target=".nav-main-collapse" id="pull" style=""> <i class="fa fa-navicon"></i> </button>
    </div>
        
    <div class="col search search-desktop last">
      <div class="search-input" >
      <form action="//www.runoob.com/" target="_blank">
        <input class="placeholder" id="s" name="s" placeholder="搜索……"  autocomplete="off" style="height: 44px;">
      </form>
      
      </div>
    </div>
  </div>
</div>



<!-- 导航栏 -->
<!-- 导航栏 -->
<div class="container navigation">
	<div class="row">
		<div class="col nav">
			<ul class="pc-nav" id="runoob-detail-nav">
				<li><a href="../">首页</a></li>
				<li><a href="../html/html-tutorial.html">HTML</a></li>
				<li><a href="../css/css-tutorial.html">CSS</a></li>
				<li><a href="../js/js-tutorial.html">JavaScript</a></li>
				<li><a href="javascript:void(0);" data-id="vue">Vue</a></li>
				<li><a href="javascript:void(0);" data-id="bootstrap">Bootstrap</a></li>
				<li><a href="../nodejs/nodejs-tutorial.html">NodeJS</a></li>
				<li><a href="../python3/python3-tutorial.html">Python3</a></li>
				<li><a href="../python/python-tutorial.html">Python2</a></li>
				<li><a href="../java/java-tutorial.html">Java</a></li>
				<li><a href="../cprogramming/c-tutorial.html">C</a></li>
				<li><a href="../cplusplus/cpp-tutorial.html">C++</a></li>
				<li><a href="../csharp/csharp-tutorial.html">C#</a></li>
				<li><a href="../go/go-tutorial.html">Go</a></li>
				<li><a href="../sql/sql-tutorial.html">SQL</a></li>
				<li><a href="../linux/linux-tutorial.html">Linux</a></li>
				<li><a href="../jquery/jquery-tutorial.html">jQuery</a></li>
				<li><a href="../browser-history">本地书签</a></li>
				<!--
			
				<li><a href="../w3cnote/knowledge-start.html" style="font-weight: bold;" onclick="_hmt.push(['_trackEvent', '星球', 'click', 'start'])" title="我的圈子">我的圈子</a></li>				
				<li><a href="javascript:;" class="runoob-pop">登录</a></li>
				-->
      		</ul>
			<ul class="mobile-nav">
				<li><a href="../">首页</a></li>
				<li><a href="../html/html-tutorial.html">HTML</a></li>
				<li><a href="../css/css-tutorial.html">CSS</a></li>
				<li><a href="../js/js-tutorial.html">JS</a></li>
				<li><a href="../browser-history">本地书签</a></li>
				<li><a href="javascript:void(0)" class="search-reveal">Search</a> </li>
			</ul>
			
		</div>
	</div>
</div>

<div class="container sub-navigation sub-navigation-articles" style="display:none">
	<div class="row">
		<div class="col nav-sub">
		<ul id="python">
			<li class="cat-item"><a href="../python3/python3-tutorial.html">Python3 教程 <i class="fa fa-external-link" aria-hidden="true"></i></a></li>
			<li class="cat-item"><a href="../python/python-tutorial.html">Python2 教程 <i class="fa fa-external-link" aria-hidden="true"></i></a></li>
		</ul>
		<ul id="vue">
			<li class="cat-item"><a href="../vue3/vue3-tutorial.html">Vue3 教程 <i class="fa fa-external-link" aria-hidden="true"></i></a></li>
			<li class="cat-item"><a href="../vue/vue-tutorial.html">vue2 教程 <i class="fa fa-external-link" aria-hidden="true"></i></a></li>
		</ul>

		<ul id="bootstrap">
			<li class="cat-item"><a href="../bootstrap/bootstrap-tutorial.html">Bootstrap3 教程 <i class="fa fa-external-link" aria-hidden="true"></i></a></li>
			<li class="cat-item"><a href="../bootstrap4/bootstrap4-tutorial.html">Bootstrap4 教程 <i class="fa fa-external-link" aria-hidden="true"></i></a></li>
			<li class="cat-item"><a href="../bootstrap5/bootstrap5-tutorial.html">Bootstrap5 教程 <i class="fa fa-external-link" aria-hidden="true"></i></a></li>
			<li class="cat-item"><a href="../bootstrap/bootstrap-v2-tutorial.html">Bootstrap2 教程 <i class="fa fa-external-link" aria-hidden="true"></i></a></li>
		</ul>
		</div>
	</div>
</div><!--  内容  -->
<div class="container main">
	<!-- 中间 -->
	<div class="row">
	
<div class="runoob-col-md2">
<div class="left-column">
	<div class="tab" style="overflow: hidden;text-overflow: ellipsis;white-space: nowrap;">
	<i class="fa fa-list" aria-hidden="true"></i> 
	<span>Ruby 教程</span>
	<a data-cate="62" href="javascript:void(0);" title="夜间模式"  id="moon"><i class="fa fa-moon-o" aria-hidden="true" style="line-height: 28px;font-size: 1.2em;margin: 2px 4px 0;"></i></a>
	<a data-cate="62" style="display:none;" href="javascript:void(0);" title="日间模式"  id="sun" ><i class="fa fa-sun-o" aria-hidden="true" style="line-height: 28px;font-size: 1.2em;margin: 2px 4px 0;line-height: 28px;
}"></i></a>

	</div>
	<div class="sidebar-box gallery-list">
		<div class="design" id="leftcolumn">
						<a target="_top" title="Ruby 教程"  href="../ruby/ruby-tutorial.html" >
			Ruby 教程			</a>
						<a target="_top" title="Ruby 简介"  href="../ruby/ruby-intro.html" >
			Ruby 简介			</a>
						<a target="_top" title="Ruby 环境"  href="../ruby/ruby-environment.html" >
			Ruby 环境			</a>
						<a target="_top" title="Ruby 安装 &#8211; Linux"  href="../ruby/ruby-installation-unix.html" >
			Ruby 安装 - Linux			</a>
						<a target="_top" title="Ruby 安装 &#8211; Windows"  href="../ruby/ruby-installation-windows.html" >
			Ruby 安装 - Windows			</a>
			<a target="_top" title="Ruby 中文编码" href="ruby-encoding.html"> Ruby 中文编码 </a>			<a target="_top" title="Ruby 命令行选项"  href="../ruby/ruby-command-line-options.html" >
			Ruby 命令行选项			</a>
						<a target="_top" title="Ruby 环境变量"  href="../ruby/ruby-environment-variables.html" >
			Ruby 环境变量			</a>
						<a target="_top" title="Ruby 语法"  href="../ruby/ruby-syntax.html" >
			Ruby 语法			</a>
			<a target="_top" title="Ruby 数据类型" href="ruby-datatypes.html"> Ruby 数据类型 </a>			<a target="_top" title="Ruby 类和对象"  href="../ruby/ruby-class.html" >
			Ruby 类和对象			</a>
						<a target="_top" title="Ruby 类案例"  href="../ruby/ruby-class-case-study.html" >
			Ruby 类案例			</a>
						<a target="_top" title="Ruby 变量"  href="../ruby/ruby-variable.html" >
			Ruby 变量			</a>
						<a target="_top" title="Ruby 运算符"  href="../ruby/ruby-operator.html" >
			Ruby 运算符			</a>
						<a target="_top" title="Ruby 注释"  href="../ruby/ruby-comment.html" >
			Ruby 注释			</a>
						<a target="_top" title="Ruby 条件判断"  href="../ruby/ruby-decision.html" >
			Ruby 条件判断			</a>
						<a target="_top" title="Ruby 循环"  href="../ruby/ruby-loop.html" >
			Ruby 循环			</a>
						<a target="_top" title="Ruby 方法"  href="../ruby/ruby-method.html" >
			Ruby 方法			</a>
						<a target="_top" title="Ruby 块"  href="../ruby/ruby-block.html" >
			Ruby 块			</a>
						<a target="_top" title="Ruby 模块（Module）"  href="../ruby/ruby-module.html" >
			Ruby 模块（Module）			</a>
						<a target="_top" title="Ruby 字符串（String）"  href="../ruby/ruby-string.html" >
			Ruby 字符串（String）			</a>
						<a target="_top" title="Ruby 数组（Array）"  href="../ruby/ruby-array.html" >
			Ruby 数组（Array）			</a>
						<a target="_top" title="Ruby 哈希（Hash）"  href="../ruby/ruby-hash.html" >
			Ruby 哈希（Hash）			</a>
						<a target="_top" title="Ruby 日期 &#038; 时间（Date &#038; Time）"  href="../ruby/ruby-date-time.html" >
			Ruby 日期 & 时间			</a>
						<a target="_top" title="Ruby 范围（Range）"  href="../ruby/ruby-range.html" >
			Ruby 范围（Range）			</a>
						<a target="_top" title="Ruby 迭代器"  href="../ruby/ruby-iterators.html" >
			Ruby 迭代器			</a>
						<a target="_top" title="Ruby 文件的输入与输出"  href="../ruby/ruby-input-output.html" >
			Ruby 文件的输入与输出			</a>
						<a target="_top" title="Ruby File 类和方法"  href="../ruby/ruby-file-methods.html" >
			Ruby File 类和方法			</a>
						<a target="_top" title="Ruby Dir 类和方法"  href="../ruby/ruby-dir-methods.html" >
			Ruby Dir 类和方法			</a>
						<a target="_top" title="Ruby 异常"  href="../ruby/ruby-exceptions.html" >
			Ruby 异常			</a>
			<br><h2 class="left"><span class="left_h2">Ruby</span> 高级教程</h2>			<a target="_top" title="Ruby 面向对象"  href="../ruby/ruby-object-oriented.html" >
			Ruby 面向对象			</a>
						<a target="_top" title="Ruby 正则表达式"  href="../ruby/ruby-regular-expressions.html" >
			Ruby 正则表达式			</a>
						<a target="_top" title="Ruby 数据库访问 &#8211; DBI 教程"  href="../ruby/ruby-database-access.html" >
			Ruby 数据库访问 - DBI 教程			</a>
			<a target="_top" title="Ruby Mysql" href="ruby-mysql-mysql2.html"> Ruby Mysql </a>			<a target="_top" title="Ruby  CGI 编程"  href="../ruby/ruby-cgi.html" >
			Ruby  CGI 编程			</a>
						<a target="_top" title="Ruby CGI方法"  href="../ruby/ruby-cgi-methods.html" >
			Ruby CGI方法			</a>
						<a target="_top" title="Ruby CGI Cookie"  href="../ruby/ruby-cgi-cookies.html" >
			Ruby CGI Cookie			</a>
						<a target="_top" title="Ruby CGI Session"  href="../ruby/ruby-cgi-sessions.html" >
			Ruby CGI Session			</a>
						<a target="_top" title="Ruby 发送邮件 &#8211; SMTP"  href="../ruby/ruby-sending-email.html" >
			Ruby 发送邮件 - SMTP			</a>
						<a target="_top" title="Ruby Socket 编程"  href="../ruby/ruby-socket-programming.html" >
			Ruby Socket 编程			</a>
						<a target="_top" title="Ruby XML, XSLT 和 XPath 教程"  href="../ruby/ruby-xml-xslt-xpath.html" >
			Ruby XML, XSLT 和 XPath 教程			</a>
						<a target="_top" title="Ruby Web Service 应用 &#8211; SOAP4R"  href="../ruby/ruby-web-services.html" >
			Ruby Web Service			</a>
						<a target="_top" title="Ruby 多线程"  href="../ruby/ruby-multithreading.html" >
			Ruby 多线程			</a>
						<a target="_top" title="Ruby JSON"  href="../ruby/ruby-json.html" >
			Ruby JSON			</a>
						<a target="_top" title="Ruby RubyGems"  href="../ruby/ruby-rubygems.html" >
			Ruby RubyGems			</a>
				
		</div>
	</div>	
</div>
</div>	<div class="col middle-column">
		
	
	<div class="article">
		
		<div class="previous-next-links">
			<div class="previous-design-link"><i style="font-size:16px;" class="fa fa-arrow-left" aria-hidden="true"></i> <a href="../ruby/ruby-exceptions.html" rel="prev"> Ruby 异常</a> </div>
			<div class="next-design-link"><a href="../ruby/ruby-regular-expressions.html" rel="next"> Ruby 正则表达式</a> <i style="font-size:16px;" class="fa fa-arrow-right" aria-hidden="true"></i></div>
		</div>
<div class="article-heading-ad" style="display: block;">
<script async src=""
     crossorigin="anonymous"></script>
<!-- 728*90 固定 -->
<ins class="adsbygoogle"
     style="display:inline-block;width:728px;height:90px"
     data-ad-client="ca-pub-5751451760833794"
     data-ad-slot="2147566827"></ins>
<script>
     (adsbygoogle = window.adsbygoogle || []).push({});
</script>
		</div>
		<div class="article-body">
		
			<div class="article-intro" id="content">
			
			<h1>Ruby <span class="color_h1">面向对象</span></h1>

<div class="tutintro">
<p>Ruby 是纯面向对象的语言，Ruby 中的一切都是以对象的形式出现。Ruby 中的每个值都是一个对象，即使是最原始的东西：字符串、数字，甚至连 true 和 false 都是对象。类本身也是一个<i>对象</i>，是 <i>Class</i> 类的一个实例。本章将向您讲解所有与 Ruby 面向对象相关的主要功能。</p>
<p>类用于指定对象的形式，它结合了数据表示法和方法，把数据整理成一个整齐的包。类中的数据和方法被称为类的成员。</p>
</div>

<h2 class="tutheader">Ruby 类定义</h2>
<p>当您定义一个类时，您实际是定义了一个数据类型的蓝图。这实际上并没有定义任何的数据，而是定义了类的名称意味着什么，也就是说，定义了类的对象将由什么组成，以及在该对象上能执行什么操作。</p>
<p>类定义以关键字 <b>class</b> 开始，后跟<b>类名称</b>，最后以一个 <b>end</b> 进行分隔表示终止该类定义。例如，我们使用关键字 class 来定义 Box 类，如下所示：</p>
<div class="example">
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-identifier">code</span><span class="hl-code">
</span><span class="hl-reserved">end</span></div>
</div>
</div>
<p>按照惯例，名称必须以大写字母开头，如果包含多个单词，每个单词首字母大写，但此间没有分隔符（例如：CamelCase）。</p>

<h2 class="tutheader">定义 Ruby 对象</h2>
<p>类提供了对象的蓝图，所以基本上，对象是根据类进行创建的。我们使用 <b>new</b> 关键字声明类的对象。下面的语句声明了类 Box 的两个对象：</p>
<div class="example">
<div class="example_code">
<div class="hl-main"><span class="hl-identifier">box1</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-code">
</span><span class="hl-identifier">box2</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span></div>
</div>
</div>

<h2 class="tutheader">initialize 方法</h2>
<p><b>initialize</b> 方法是一个标准的 Ruby 类方法，是类的构造函数，与其他面向对象编程语言中的 <b>constructor</b> 工作原理类似。当您想要在创建对象的同时初始化一些类变量，initialize 方法就派上用场了。该方法带有一系列参数，与其他 Ruby 方法一样，使用该方法时，必须在前面放置 <b>def</b> 关键字，如下所示：</p>
<div class="example">
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span></div>
</div>
</div>

<h2 class="tutheader">实例变量</h2>
<p><b>实例变量</b>是类属性，它们在使用类创建对象时就变成对象的属性。每个对象的属性是单独赋值的，和其他对象之间不共享值。在类的内部，是使用 @ 运算符访问这些属性，在类的外部，则是使用称为<b>访问器方法</b>的<b>公共</b>方法进行访问。下面我们以上面定义的类 <b>Box</b> 为实例，把 @width 和 @height 作为类 Box 的实例变量。</p>
<div class="example">
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-comment">#</span><span class="hl-comment"> 给实例变量赋值</span><span class="hl-comment"></span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span></div>
</div>
</div>

<h2 class="tutheader">访问器(getter) & 设置器(setter)方法</h2>
<p>为了在类的外部读取类中已定义的变量，我们可以通过定义访问器(getter)方法来访问。下面的实例演示了访问器方法的用法：</p> 
<div class="example">
<h2 class="example">实例</h2>
<div class="example_code">
<div class="hl-main"><span class="hl-comment">#</span><span class="hl-comment">!/usr/bin/ruby -w</span><span class="hl-comment"></span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 定义类</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 构造函数</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
 
   </span><span class="hl-comment">#</span><span class="hl-comment"> 访问器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">printWidth</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
 
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">printHeight</span><span class="hl-code">
      </span><span class="hl-var">@height</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 创建对象，初始化盒子的高度与宽度</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-number">10</span><span class="hl-code">, </span><span class="hl-number">20</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 使用访问器方法</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">x</span><span class="hl-code"> = </span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">printWidth</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">
</span><span class="hl-identifier">y</span><span class="hl-code"> = </span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">printHeight</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">盒子宽度 : #{x}</span><span class="hl-quotes">&quot;</span><span class="hl-code">
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">盒子高度 : #{y}</span><span class="hl-quotes">&quot;</span></div>
</div><br>
<a target="_blank" href="../try/runcode.php?filename=class_demo&type=ruby" class="tryitbtn" rel="noopener noreferrer">尝试一下 »</a>
</div>
<p>当上面的代码执行时，它会产生以下结果：</p>
<pre>
盒子宽度 : 10
盒子高度 : 20
</pre>
<p>与用于访问变量值的访问器方法类似，Ruby 提供了一种在类的外部将参数传入类中已定义的变量，也就是所谓的<b>设置器方法</b>，定义如下：</p> 
<div class="example">
<h2 class="example">实例</h2>
<div class="example_code">
<div class="hl-main"><span class="hl-comment">#</span><span class="hl-comment">!/usr/bin/ruby -w</span><span class="hl-comment"></span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 定义类</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 构造器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
 
   </span><span class="hl-comment">#</span><span class="hl-comment"> 访问器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getWidth</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getHeight</span><span class="hl-code">
      </span><span class="hl-var">@height</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
 
   </span><span class="hl-comment">#</span><span class="hl-comment"> 设置器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">setWidth</span><span class="hl-code">=</span><span class="hl-brackets">(</span><span class="hl-identifier">value</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code"> = </span><span class="hl-identifier">value</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">setHeight</span><span class="hl-code">=</span><span class="hl-brackets">(</span><span class="hl-identifier">value</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">value</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 创建对象</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-number">10</span><span class="hl-code">, </span><span class="hl-number">20</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 使用设置器方法</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">setWidth</span><span class="hl-code"> = </span><span class="hl-number">30</span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">setHeight</span><span class="hl-code"> = </span><span class="hl-number">50</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 使用访问器方法</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">x</span><span class="hl-code"> = </span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">getWidth</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">
</span><span class="hl-identifier">y</span><span class="hl-code"> = </span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">getHeight</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">盒子宽度 : #{x}</span><span class="hl-quotes">&quot;</span><span class="hl-code">
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">盒子高度 : #{y}</span><span class="hl-quotes">&quot;</span></div>
</div><br>
<a target="_blank" href="../try/runcode.php?filename=class_demo2&type=ruby" class="tryitbtn" rel="noopener noreferrer">尝试一下 »</a>
</div>
<p>当上面的代码执行时，它会产生以下结果：</p>
<pre>
盒子宽度 : 30
盒子高度 : 50
</pre>

<blockquote>
<p>由于两种方法非常常用，Ruby 定义了 <strong>attr_accessor :variable_name、attr_reader :variable_name、attr_writer :variable_name</strong> 三种属性声明方法。其中：<strong>accessor=reader+writer</strong>。</p>
<p>
同时注意：变量名前一定要带 <span class="marked">:</span> ，变量名之间要用 <span class="marked">,</span>  分割。</p></blockquote>


<h2 class="tutheader">实例方法</h2>
<p><b>实例方法</b>的定义与其他方法的定义一样，都是使用 <b>def</b> 关键字，但它们只能通过类实例来使用，如下面实例所示。它们的功能不限于访问实例变量，也能按照您的需求做更多其他的任务。</p>
<div class="example">
<h2 class="example">实例</h2>
<div class="example_code">
<div class="hl-main"><span class="hl-comment">#</span><span class="hl-comment">!/usr/bin/ruby -w</span><span class="hl-comment"></span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 定义类</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 构造方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 实例方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getArea</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code"> * </span><span class="hl-var">@height</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 创建对象</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-number">10</span><span class="hl-code">, </span><span class="hl-number">20</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 调用实例方法</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">getArea</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Area of the box is : #{a}</span><span class="hl-quotes">&quot;</span></div>
</div><br>
<a target="_blank" href="../try/runcode.php?filename=class_demo3&type=ruby" class="tryitbtn" rel="noopener noreferrer">尝试一下 »</a>
</div>
<p>当上面的代码执行时，它会产生以下结果：</p>
<pre>
Area of the box is : 200
</pre>

<h2 class="tutheader">类方法 & 类变量</h2>
<p><b>类变量</b>是在类的所有实例中共享的变量。换句话说，类变量的实例可以被所有的对象实例访问。类变量以两个 @ 字符（@@）作为前缀，类变量必须在类定义中被初始化，如下面实例所示。</p>
<p><b>类方法</b>使用 <b>def self.methodname()</b> 定义，类方法以 end 分隔符结尾。类方法可使用带有类名称的 <b>classname.methodname</b> 形式调用，如下面实例所示：</p>
<div class="example">
<h2 class="example">实例</h2>
<div class="example_code">
<div class="hl-main"><span class="hl-comment">#</span><span class="hl-comment">!/usr/bin/ruby -w</span><span class="hl-comment"></span><span class="hl-code">
 
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 初始化类变量</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-var">@@count</span><span class="hl-code"> = </span><span class="hl-number">0</span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-comment">#</span><span class="hl-comment"> 给实例变量赋值</span><span class="hl-comment"></span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
 
      </span><span class="hl-var">@@count</span><span class="hl-code"> += </span><span class="hl-number">1</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
 
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-reserved">self</span><span class="hl-code">.</span><span class="hl-identifier">printCount</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Box count is : #@@count</span><span class="hl-quotes">&quot;</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 创建两个对象</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box1</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-number">10</span><span class="hl-code">, </span><span class="hl-number">20</span><span class="hl-brackets">)</span><span class="hl-code">
</span><span class="hl-identifier">box2</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-number">30</span><span class="hl-code">, </span><span class="hl-number">100</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 调用类方法来输出盒子计数</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">printCount</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span></div>
</div><br>
<a target="_blank" href="../try/runcode.php?filename=class_demo4&type=ruby" class="tryitbtn" rel="noopener noreferrer">尝试一下 »</a>
</div>
<p>当上面的代码执行时，它会产生以下结果：</p>
<pre>
Box count is : 2
</pre>

<h2 class="tutheader">to_s 方法</h2>
<p>您定义的任何类都有一个 <b>to_s</b> 实例方法来返回对象的字符串表示形式。下面是一个简单的实例，根据 width 和 height 表示 Box 对象：</p>
<div class="example">
<h2 class="example">实例</h2>
<div class="example_code">
<div class="hl-main"><span class="hl-comment">#</span><span class="hl-comment">!/usr/bin/ruby -w</span><span class="hl-comment"></span><span class="hl-code">
 
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 构造器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 定义 to_s 方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">to_s</span><span class="hl-code">
      </span><span class="hl-quotes">&quot;</span><span class="hl-string">(w:#@width,h:#@height)</span><span class="hl-quotes">&quot;</span><span class="hl-code">  </span><span class="hl-comment">#</span><span class="hl-comment"> 对象的字符串格式</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 创建对象</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-number">10</span><span class="hl-code">, </span><span class="hl-number">20</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 自动调用 to_s 方法</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">String representation of box is : #{box}</span><span class="hl-quotes">&quot;</span></div>
</div><br>
<a target="_blank" href="../try/runcode.php?filename=class_demo5&type=ruby" class="tryitbtn" rel="noopener noreferrer">尝试一下 »</a>
</div>
<p>当上面的代码执行时，它会产生以下结果：</p>
<pre>
String representation of box is : (w:10,h:20)
</pre>

<h2 class="tutheader">访问控制</h2>
<p>Ruby 为您提供了三个级别的实例方法保护，分别是 <b>public、private 或 protected</b>。Ruby 不在实例和类变量上应用任何访问控制。</p>
<ul class="list">
<li><b>Public 方法：</b> Public 方法可被任意对象调用。默认情况下，方法都是 public 的，除了 initialize 方法总是 private 的。</li>
<li><b>Private 方法：</b> Private 方法不能从类外部访问或查看。只有类方法可以访问私有成员。</li>
<li><b>Protected 方法：</b> Protected 方法只能被类及其子类的对象调用。访问也只能在类及其子类内部进行。</li>
</ul>
<p>下面是一个简单的实例，演示了这三种修饰符的语法：</p>
<div class="example">
<h2 class="example">实例</h2>
<div class="example_code">
<div class="hl-main"><span class="hl-comment">#</span><span class="hl-comment">!/usr/bin/ruby -w</span><span class="hl-comment"></span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 定义类</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 构造器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
 
   </span><span class="hl-comment">#</span><span class="hl-comment"> 实例方法默认是 public 的</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getArea</span><span class="hl-code">
      </span><span class="hl-identifier">getWidth</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code"> * </span><span class="hl-identifier">getHeight</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
 
   </span><span class="hl-comment">#</span><span class="hl-comment"> 定义 private 的访问器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getWidth</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getHeight</span><span class="hl-code">
      </span><span class="hl-var">@height</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> make them private</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">private</span><span class="hl-code"> :</span><span class="hl-identifier">getWidth</span><span class="hl-code">, :</span><span class="hl-identifier">getHeight</span><span class="hl-code">
 
   </span><span class="hl-comment">#</span><span class="hl-comment"> 用于输出面积的实例方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">printArea</span><span class="hl-code">
      </span><span class="hl-var">@area</span><span class="hl-code"> = </span><span class="hl-identifier">getWidth</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code"> * </span><span class="hl-identifier">getHeight</span><span class="hl-code">
      </span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Big box area is : #@area</span><span class="hl-quotes">&quot;</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 让实例方法是 protected 的</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">protected</span><span class="hl-code"> :</span><span class="hl-identifier">printArea</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 创建对象</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-number">10</span><span class="hl-code">, </span><span class="hl-number">20</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 调用实例方法</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">getArea</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Area of the box is : #{a}</span><span class="hl-quotes">&quot;</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 尝试调用 protected 的实例方法</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">printArea</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span></div>
</div><br>
<a target="_blank" href="../try/runcode.php?filename=class_demo6&type=ruby" class="tryitbtn" rel="noopener noreferrer">尝试一下 »</a>
</div>
<p>当上面的代码执行时，它会产生以下结果。在这里，第一种方法调用成功，但是第二方法会产生一个问题。</p>
<pre>
Area of the box is : 200
test.rb:42: protected method `printArea' called for #
&lt;Box:0xb7f11280 @height=20, @width=10&gt; (NoMethodError)
</pre>

<h2 class="tutheader">类的继承</h2>
<p>继承，是面向对象编程中最重要的概念之一。继承允许我们根据另一个类定义一个类，这样使得创建和维护应用程序变得更加容易。</p>
<p>继承有助于重用代码和快速执行，不幸的是，Ruby 不支持多继承，但是 Ruby 支持 <b>mixins</b>。mixin 就像是多继承的一个特定实现，在多继承中，只有接口部分是可继承的。</p>
<p>当创建类时，程序员可以直接指定新类继承自某个已有类的成员，这样就不用从头编写新的数据成员和成员函数。这个已有类被称为<b>基类或父类</b>，新类被称为<b>派生类或子类</b>。</p>
<p>Ruby 也提供了子类化的概念，子类化即继承，下面的实例解释了这个概念。扩展一个类的语法非常简单。只要添加一个 &lt; 字符和父类的名称到类语句中即可。例如，下面定义了类 <i>BigBox</i> 是 <i>Box</i> 的子类：</p>
<div class="example">
<h2 class="example">实例</h2>
<div class="example_code">
<div class="hl-main"><span class="hl-comment">#</span><span class="hl-comment">!/usr/bin/ruby -w</span><span class="hl-comment"></span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 定义类</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 构造器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 实例方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getArea</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code"> * </span><span class="hl-var">@height</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 定义子类</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">BigBox</span><span class="hl-code"> &lt; </span><span class="hl-identifier">Box</span><span class="hl-code">
 
   </span><span class="hl-comment">#</span><span class="hl-comment"> 添加一个新的实例方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">printArea</span><span class="hl-code">
      </span><span class="hl-var">@area</span><span class="hl-code"> = </span><span class="hl-var">@width</span><span class="hl-code"> * </span><span class="hl-var">@height</span><span class="hl-code">
      </span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Big box area is : #@area</span><span class="hl-quotes">&quot;</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 创建对象</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code"> = </span><span class="hl-identifier">BigBox</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-number">10</span><span class="hl-code">, </span><span class="hl-number">20</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 输出面积</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">printArea</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span></div>
</div><br>
<a target="_blank" href="../try/runcode.php?filename=class_demo7&type=ruby" class="tryitbtn" rel="noopener noreferrer">尝试一下 »</a>
</div>

<p>当上面的代码执行时，它会产生以下结果：</p>
<pre>
Big box area is : 200
</pre>

<h2 class="tutheader">方法重载</h2>
<p>虽然您可以在派生类中添加新的功能，但有时您可能想要改变已经在父类中定义的方法的行为。这时您可以保持方法名称不变，重载方法的功能即可，如下面实例所示：</p>
<div class="example">
<h2 class="example">实例</h2>
<div class="example_code">
<div class="hl-main"><span class="hl-comment">#</span><span class="hl-comment">!/usr/bin/ruby -w</span><span class="hl-comment"></span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 定义类</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 构造器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 实例方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getArea</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code"> * </span><span class="hl-var">@height</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 定义子类</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">BigBox</span><span class="hl-code"> &lt; </span><span class="hl-identifier">Box</span><span class="hl-code">
 
   </span><span class="hl-comment">#</span><span class="hl-comment"> 改变已有的 getArea 方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getArea</span><span class="hl-code">
      </span><span class="hl-var">@area</span><span class="hl-code"> = </span><span class="hl-var">@width</span><span class="hl-code"> * </span><span class="hl-var">@height</span><span class="hl-code">
      </span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Big box area is : #@area</span><span class="hl-quotes">&quot;</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 创建对象</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code"> = </span><span class="hl-identifier">BigBox</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-number">10</span><span class="hl-code">, </span><span class="hl-number">20</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 使用重载的方法输出面积</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">getArea</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span></div>
</div><br>
<a target="_blank" href="../try/runcode.php?filename=class_demo8&type=ruby" class="tryitbtn" rel="noopener noreferrer">尝试一下 »</a>
</div>

<p>以上实例运行输出结果为：</p>
<pre>
Big box area is : 200
</pre>
<h2 class="tutheader">运算符重载</h2>
<p>我们希望使用 + 运算符执行两个 Box 对象的向量加法，使用 * 运算符来把 Box 的 width 和 height 相乘，使用一元运算符 - 对 Box 的 width 和 height 求反。下面是一个带有数学运算符定义的 Box 类版本：</p>
<div class="example">
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
  </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-comment">#</span><span class="hl-comment"> 初始化 width 和 height</span><span class="hl-comment"></span><span class="hl-code">
    </span><span class="hl-var">@width</span><span class="hl-code">,</span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
  </span><span class="hl-reserved">end</span><span class="hl-code">
 
  </span><span class="hl-reserved">def</span><span class="hl-code"> +</span><span class="hl-brackets">(</span><span class="hl-identifier">other</span><span class="hl-brackets">)</span><span class="hl-code">         </span><span class="hl-comment">#</span><span class="hl-comment"> 定义 + 来执行向量加法</span><span class="hl-comment"></span><span class="hl-code">
    </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-var">@width</span><span class="hl-code"> + </span><span class="hl-identifier">other</span><span class="hl-code">.</span><span class="hl-identifier">width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> + </span><span class="hl-identifier">other</span><span class="hl-code">.</span><span class="hl-identifier">height</span><span class="hl-brackets">)</span><span class="hl-code">
  </span><span class="hl-reserved">end</span><span class="hl-code">
 
  </span><span class="hl-reserved">def</span><span class="hl-code"> -@               </span><span class="hl-comment">#</span><span class="hl-comment"> 定义一元运算符 - 来对 width 和 height 求反</span><span class="hl-comment"></span><span class="hl-code">
    </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-code">-</span><span class="hl-var">@width</span><span class="hl-code">, -</span><span class="hl-var">@height</span><span class="hl-brackets">)</span><span class="hl-code">
  </span><span class="hl-reserved">end</span><span class="hl-code">
 
  </span><span class="hl-reserved">def</span><span class="hl-code"> *</span><span class="hl-brackets">(</span><span class="hl-identifier">scalar</span><span class="hl-brackets">)</span><span class="hl-code">        </span><span class="hl-comment">#</span><span class="hl-comment"> 执行标量乘法</span><span class="hl-comment"></span><span class="hl-code">
    </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-var">@width</span><span class="hl-code">*</span><span class="hl-identifier">scalar</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code">*</span><span class="hl-identifier">scalar</span><span class="hl-brackets">)</span><span class="hl-code">
  </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span></div>
</div>
</div>

<h2 class="tutheader">冻结对象</h2>
<p>有时候，我们想要防止对象被改变。在 Object 中，freeze 方法可实现这点，它能有效地把一个对象变成一个常量。任何对象都可以通过调用 <b>Object.freeze</b> 进行冻结。冻结对象不能被修改，也就是说，您不能改变它的实例变量。</p>
<p>您可以使用 <b>Object.frozen?</b> 方法检查一个给定的对象是否已经被冻结。如果对象已被冻结，该方法将返回 true，否则返回一个 false 值。下面的实例解释了这个概念：</p>
<div class="example">
<h2 class="example">实例</h2>
<div class="example_code">
<div class="hl-main"><span class="hl-comment">#</span><span class="hl-comment">!/usr/bin/ruby -w</span><span class="hl-comment"></span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 定义类</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 构造器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
 
   </span><span class="hl-comment">#</span><span class="hl-comment"> 访问器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getWidth</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getHeight</span><span class="hl-code">
      </span><span class="hl-var">@height</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
 
   </span><span class="hl-comment">#</span><span class="hl-comment"> 设置器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">setWidth</span><span class="hl-code">=</span><span class="hl-brackets">(</span><span class="hl-identifier">value</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code"> = </span><span class="hl-identifier">value</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">setHeight</span><span class="hl-code">=</span><span class="hl-brackets">(</span><span class="hl-identifier">value</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">value</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 创建对象</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-number">10</span><span class="hl-code">, </span><span class="hl-number">20</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 让我们冻结该对象</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">freeze</span><span class="hl-code">
</span><span class="hl-reserved">if</span><span class="hl-brackets">(</span><span class="hl-code"> </span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">frozen</span><span class="hl-code">? </span><span class="hl-brackets">)</span><span class="hl-code">
   </span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Box object is frozen object</span><span class="hl-quotes">&quot;</span><span class="hl-code">
</span><span class="hl-reserved">else</span><span class="hl-code">
   </span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Box object is normal object</span><span class="hl-quotes">&quot;</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 现在尝试使用设置器方法</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">setWidth</span><span class="hl-code"> = </span><span class="hl-number">30</span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">setHeight</span><span class="hl-code"> = </span><span class="hl-number">50</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 使用访问器方法</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">x</span><span class="hl-code"> = </span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">getWidth</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">
</span><span class="hl-identifier">y</span><span class="hl-code"> = </span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">getHeight</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Width of the box is : #{x}</span><span class="hl-quotes">&quot;</span><span class="hl-code">
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Height of the box is : #{y}</span><span class="hl-quotes">&quot;</span></div>
</div><br>
<a target="_blank" href="../try/runcode.php?filename=class_demo9&type=ruby" class="tryitbtn" rel="noopener noreferrer">尝试一下 »</a>
</div>

<p>当上面的代码执行时，它会产生以下结果：</p>
<pre>
Box object is frozen object
test.rb:20:in `setWidth=': can't modify frozen object (TypeError)
        from test.rb:39
</pre>

<h2 class="tutheader">类常量</h2>
<p>您可以在类的内部定义一个常量，通过把一个直接的数值或字符串值赋给一个变量来定义的，常量的定义不需要使用 @ 或 @@。按照惯例，常量的名称使用大写。</p>
<p>一旦常量被定义，您就不能改变它的值，您可以在类的内部直接访问常量，就像是访问变量一样，但是如果您想要在类的外部访问常量，那么您必须使用 <b>classname::constant</b>，如下面实例所示。</p>
<div class="example">
<h2 class="example">实例</h2>
<div class="example_code">
<div class="hl-main"><span class="hl-comment">#</span><span class="hl-comment">!/usr/bin/ruby -w</span><span class="hl-comment"></span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 定义类</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-identifier">BOX_COMPANY</span><span class="hl-code"> = </span><span class="hl-quotes">&quot;</span><span class="hl-string">TATA Inc</span><span class="hl-quotes">&quot;</span><span class="hl-code">
   </span><span class="hl-identifier">BOXWEIGHT</span><span class="hl-code"> = </span><span class="hl-number">10</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 构造器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 实例方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getArea</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code"> * </span><span class="hl-var">@height</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 创建对象</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-number">10</span><span class="hl-code">, </span><span class="hl-number">20</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 调用实例方法</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-identifier">box</span><span class="hl-code">.</span><span class="hl-identifier">getArea</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Area of the box is : #{a}</span><span class="hl-quotes">&quot;</span><span class="hl-code">
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">::</span><span class="hl-identifier">BOX_COMPANY</span><span class="hl-code">
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Box weight is: #{Box::BOXWEIGHT}</span><span class="hl-quotes">&quot;</span></div>
</div><br>
<a target="_blank" href="../try/runcode.php?filename=class_demo10&type=ruby" class="tryitbtn" rel="noopener noreferrer">尝试一下 »</a>
</div>
<p>当上面的代码执行时，它会产生以下结果：</p>
<pre>
Area of the box is : 200
TATA Inc
Box weight is: 10
</pre>
<p>类常量可被继承，也可像实例方法一样被重载。</p>

<h2 class="tutheader">使用 allocate 创建对象</h2>
<p>可能有一种情况，您想要在不调用对象构造器 <b>initialize</b> 的情况下创建对象，即，使用 new 方法创建对象，在这种情况下，您可以调用 allocate 来创建一个未初始化的对象，如下面实例所示：</p>
<div class="example">
<h2 class="example">实例</h2>
<div class="example_code">
<div class="hl-main"><span class="hl-comment">#</span><span class="hl-comment">!/usr/bin/ruby -w</span><span class="hl-comment"></span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 定义类</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-reserved">attr_accessor</span><span class="hl-code"> :</span><span class="hl-identifier">width</span><span class="hl-code">, :</span><span class="hl-identifier">height</span><span class="hl-code">
 
   </span><span class="hl-comment">#</span><span class="hl-comment"> 构造器方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">initialize</span><span class="hl-brackets">(</span><span class="hl-identifier">w</span><span class="hl-code">,</span><span class="hl-identifier">h</span><span class="hl-brackets">)</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code">, </span><span class="hl-var">@height</span><span class="hl-code"> = </span><span class="hl-identifier">w</span><span class="hl-code">, </span><span class="hl-identifier">h</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
 
   </span><span class="hl-comment">#</span><span class="hl-comment"> 实例方法</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-reserved">def</span><span class="hl-code"> </span><span class="hl-identifier">getArea</span><span class="hl-code">
      </span><span class="hl-var">@width</span><span class="hl-code"> * </span><span class="hl-var">@height</span><span class="hl-code">
   </span><span class="hl-reserved">end</span><span class="hl-code">
</span><span class="hl-reserved">end</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 使用 new 创建对象</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box1</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">new</span><span class="hl-brackets">(</span><span class="hl-number">10</span><span class="hl-code">, </span><span class="hl-number">20</span><span class="hl-brackets">)</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 使用 allocate 创建另一个对象</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">box2</span><span class="hl-code"> = </span><span class="hl-identifier">Box</span><span class="hl-code">.</span><span class="hl-identifier">allocate</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 使用 box1 调用实例方法</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-identifier">box1</span><span class="hl-code">.</span><span class="hl-identifier">getArea</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Area of the box is : #{a}</span><span class="hl-quotes">&quot;</span><span class="hl-code">
 
</span><span class="hl-comment">#</span><span class="hl-comment"> 使用 box2 调用实例方法</span><span class="hl-comment"></span><span class="hl-code">
</span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-identifier">box2</span><span class="hl-code">.</span><span class="hl-identifier">getArea</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">
</span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Area of the box is : #{a}</span><span class="hl-quotes">&quot;</span></div>
</div><br>
<a target="_blank" href="../try/runcode.php?filename=class_demo11&type=ruby" class="tryitbtn" rel="noopener noreferrer">尝试一下 »</a>
</div>
<p>当上面的代码执行时，它会产生以下结果：</p>
<pre>
Area of the box is : 200
test.rb:14: warning: instance variable @width not initialized
test.rb:14: warning: instance variable @height not initialized
test.rb:14:in `getArea': undefined method `*' 
   for nil:NilClass (NoMethodError) from test.rb:29
</pre>

<h2 class="tutheader">类信息</h2>
<p> Ruby的 self 和 Java 的 this 有相似之处，但又大不相同。Java的方法都是在实例方法中引用，所以this一般都是指向当前对象的。而Ruby的代码逐行执行，所以在不同的上下文(context)self就有了不同的含义。让我们来看看下面的实例：.</p>
<div class="example">
<h2 class="example">实例</h2>
<div class="example_code">
<div class="hl-main"><span class="hl-comment">#</span><span class="hl-comment">!/usr/bin/ruby -w</span><span class="hl-comment"></span><span class="hl-code">
 
</span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Box</span><span class="hl-code">
   </span><span class="hl-comment">#</span><span class="hl-comment"> 输出类信息</span><span class="hl-comment"></span><span class="hl-code">
   </span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Class of self = #{self.class}</span><span class="hl-quotes">&quot;</span><span class="hl-code">
   </span><span class="hl-identifier">puts</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Name of self = #{self.name}</span><span class="hl-quotes">&quot;</span><span class="hl-code">
</span><span class="hl-reserved">end</span></div>
</div><br>
<a target="_blank" href="../try/runcode.php?filename=class_demo12&type=ruby" class="tryitbtn" rel="noopener noreferrer">尝试一下 »</a>
</div>
<p>当上面的代码执行时，它会产生以下结果：</p>
<pre>
Class of self = Class
Name of self = Box
</pre>
<p>这意味着类定义可通过把该类作为当前对象来执行，同时也意味着元类和父类中的该方法在方法定义执行期间是可用的。</p>			<!-- 其他扩展 -->
						
			</div>
			
		</div>
		
		<div class="previous-next-links">
			<div class="previous-design-link"><i style="font-size:16px;" class="fa fa-arrow-left" aria-hidden="true"></i> <a href="../ruby/ruby-exceptions.html" rel="prev"> Ruby 异常</a> </div>
			<div class="next-design-link"><a href="../ruby/ruby-regular-expressions.html" rel="next"> Ruby 正则表达式</a> <i style="font-size:16px;" class="fa fa-arrow-right" aria-hidden="true"></i></div>
		</div>
		<!-- 笔记列表 -->
		<style>
.wrapper {
  /*text-transform: uppercase; */
  background: #ececec;
  color: #555;
  cursor: help;
  font-family: "Gill Sans", Impact, sans-serif;
  font-size: 20px;
  position: relative;
  text-align: center;
  width: 200px;
  -webkit-transform: translateZ(0); /* webkit flicker fix */
  -webkit-font-smoothing: antialiased; /* webkit text rendering fix */
}

.wrapper .tooltip {
  white-space: nowrap;
  font-size: 14px;
  text-align: left;
  background: #96b97d;
  bottom: 100%;
  color: #fff;
  display: block;
  left: -25px;
  margin-bottom: 15px;
  opacity: 0;
  padding: 14px;
  pointer-events: none;
  position: absolute;
  
  -webkit-transform: translateY(10px);
     -moz-transform: translateY(10px);
      -ms-transform: translateY(10px);
       -o-transform: translateY(10px);
          transform: translateY(10px);
  -webkit-transition: all .25s ease-out;
     -moz-transition: all .25s ease-out;
      -ms-transition: all .25s ease-out;
       -o-transition: all .25s ease-out;
          transition: all .25s ease-out;
  -webkit-box-shadow: 2px 2px 6px rgba(0, 0, 0, 0.28);
     -moz-box-shadow: 2px 2px 6px rgba(0, 0, 0, 0.28);
      -ms-box-shadow: 2px 2px 6px rgba(0, 0, 0, 0.28);
       -o-box-shadow: 2px 2px 6px rgba(0, 0, 0, 0.28);
          box-shadow: 2px 2px 6px rgba(0, 0, 0, 0.28);
}
.tooltip a {
	color:#fff;
}
/* This bridges the gap so you can mouse into the tooltip without it disappearing */
.wrapper .tooltip:before {
  bottom: -20px;
  content: " ";
  display: block;
  height: 20px;
  left: 0;
  position: absolute;
  width: 100%;
}  

/* CSS Triangles - see Trevor's post */
.wrapper .tooltip:after {
  border-left: solid transparent 10px;
  border-right: solid transparent 10px;
  border-top: solid #96b97d 10px;
  bottom: -10px;
  content: " ";
  height: 0;
  left: 20%;
  margin-left: -13px;
  position: absolute;
  width: 0;
}
.wrapper .tooltip1 {
	margin-left: 50px;
	padding-top: 0px;
}
/*
.wrapper:hover .tooltip {
  opacity: 1;
  pointer-events: auto;
  -webkit-transform: translateY(0px);
     -moz-transform: translateY(0px);
      -ms-transform: translateY(0px);
       -o-transform: translateY(0px);
          transform: translateY(0px);
}
*/
/* IE can just show/hide with no transition */
.lte8 .wrapper .tooltip {
  display: none;
}

.lte8 .wrapper:hover .tooltip {
  display: block;
}

</style>

<link rel="stylesheet" href="../0/upvotejs.css">
<script src=""></script>
<script src=""></script>
<div id="respond" class="no_webshot"> 
		<div class="comment-signarea" style=" padding: 20px 20px;"> 
	<h3 class="text-muted" id="share_code" style="color: #799961;"><i class="fa fa-pencil-square-o" aria-hidden="true"></i> 点我分享笔记</h3>
	<!--
	<p style="font-size:14px;">笔记需要是本篇文章的内容扩展！</p><br>
	<p style="font-size:12px;"><a href="../tougao" target="_blank">文章投稿，可点击这里</a></p>
	<p style="font-size:14px;"><a href="../w3cnote/runoob-user-test-intro.html#invite" target="_blank">注册邀请码获取方式</a></p>
		<h3 class="text-muted"><i class="fa fa-info-circle" aria-hidden="true"></i> 分享笔记前必须<a href="javascript:;" class="runoob-pop">登录</a>！</h3>
		<p><a href="../w3cnote/runoob-user-test-intro.html#invite" target="_blank">注册邀请码获取方式</a></p>-->
	</div>
		
	<form action="/wp-content/themes/runoob/option/addnote.php" method="post" id="commentform" style="display:none;">
		<div class="comt">
			<div class="comt-title">
				<i style="font-size:36px;" class="fa fa-user-circle" aria-hidden="true"></i>				<p><a id="cancel-comment-reply-link" href="javascript:;">取消</a></p>
			</div>
			<div class="comt-box">
			<div id="mded"></div>
			
				<div class="comt-ctrl">
					<div class="comt-tips"><input type='hidden' name='comment_post_ID' value='7267' id='comment_post_ID' />
<input type='hidden' name='comment_parent' id='comment_parent' value='0' />
</div>
					<button type="submit" name="submit" id="submit" tabindex="5"><i class="fa fa-pencil" aria-hidden="true"></i> 分享笔记</button>
				</div>
			</div>
		
				
					<div class="comt-comterinfo"> 
						<ul id="comment-author-info">
							<li class="form-inline"><label class="hide" for="author">昵称</label><input class="ipt" type="text" name="author" id="author" value="" tabindex="2" placeholder="昵称"><span class="text-muted">昵称 (必填)</span></li>
							<li class="form-inline"><label class="hide" for="email">邮箱</label><input class="ipt" type="text" name="email" id="email" value="" tabindex="3" placeholder="邮箱"><span class="text-muted">邮箱 (必填)</span></li>
							<li class="form-inline"><label class="hide" for="url">引用地址</label><input class="ipt" type="text" name="url" id="url" value="" tabindex="4" placeholder="引用地址"><span class="text-muted">引用地址</span></li>
						</ul>
					</div>
				
			
		</div>

	</form>
	</div>
<script type="text/javascript">
$(function() {
	//初始化编辑器
	
	var editor = new Simditor({
	  textarea: $('#mded'),
	  placeholder: '写笔记...',
	  upload:false,
	 // upload: {url:'/api/comment_upload_file.php',params: null,fileKey: 'upload_file',connectionCount: 1,leaveConfirm: '文件正在上传，您确定离开?'},
	  defaultImage: 'https://www.runoob.com/images/logo.png',
	  codeLanguages: '',
	  autosave: 'editor-content',
	  toolbar: [  'bold','code','ul','ol','image' ]
	});
	editor.on('selectionchanged', function() {
		$(".code-popover").hide();
	});

	// 提交数据
	$("#share_code").click(function() {
		$(".comment-signarea").hide();
		$("#commentform").show();
		
	});
	$("#user_add_note").click(function() {
		$(".comment-signarea").hide();
		$("#commentform").show();
		$('html, body').animate({
       	    scrollTop: $("#respond").offset().top
    	}, 200);
	});

	// 提交笔记
	var commentform=$('#commentform');
	commentform.prepend('<div id="comment-status" style="display:none;" ></div>');
	var statusdiv=$('#comment-status');
	
	commentform.submit(function(e){
		e.preventDefault();
		var noteContent = editor.getValue();
		// console.log(noteContent);
		noteContent = noteContent.replace(/<pre><code>/g,"<pre>");
		noteContent = noteContent.replace(/<\/code><\/pre>/g,"</pre>");
		
		// 系列化表单数据
		var comment_parent = 0;
		var is_user_logged_in = $("#is_user_logged_in").val();
		var comment_post_ID =  7267;
		var _wp_unfiltered_html_comment = $("#_wp_unfiltered_html_comment").val();
		var comment = noteContent;
		var author = $("#author").val();
		var url = $("#url").val();
		var email = $("#email").val();
		if(isBlank(author) && is_user_logged_in==0) {
			statusdiv.html('<p  class="ajax-error">请输入昵称！</p>').show();
		} else if(isBlank(email)  && is_user_logged_in==0) {
			statusdiv.html('<p  class="ajax-error">请输入邮箱！</p>').show();
		} else {
			// var formdata=commentform.serialize() + "&comment=" + noteContent ;
			// 添加状态信息
			statusdiv.html('<p>Processing...</p>').show();
			// 获取表单提交地址
			var formurl=commentform.attr('action');
			
			// 异步提交
			$.ajax({
					type: 'post',
					url: formurl,
					dataType:'json',
					data: {"comment_parent":comment_parent,"comment_post_ID":comment_post_ID, "_wp_unfiltered_html_comment":_wp_unfiltered_html_comment,"comment":comment,"url":url, "email":email,"author":author},
					error: function(XMLHttpRequest, textStatus, errorThrown){
					statusdiv.html('<p class="ajax-error" >数据不完整或表单提交太快了！</p>').show();
				},
				success: function(data, textStatus){
					if(data.errorno=="0") {
						$("#submit").prop('disabled', true);
						statusdiv.html('<p class="ajax-success" >笔记已提交审核，感谢分享笔记！</p>').show();
						alert('笔记已提交审核，感谢分享笔记！');
					}else{
						statusdiv.html('<p class="ajax-error" >'+data.msg+'</p>').show();
					}
					commentform.find('textarea[name=comment]').val('');
				}
			});
			setTimeout(function(){
		        $("#submit").prop('disabled', false);
		    }, 10*1000);
		}
		return false;

	});
	$(".comt-author").click(function() {
		href = $(this).children("a").attr("href");
		if(href.indexOf("/note/")!=-1) {
			var win = window.open(href, '_blank');
  			win.focus();
		}
	});
	$(".comt-meta span").hover(function(){
		$(this).children(".tooltip").css({ "opacity": 1, "pointer-events": "auto"});
	},function(){
		$(this).children(".tooltip").removeAttr("style");
	});
	/*
	$(".wrapper i").hover(function(){
		$(this).siblings(".tooltip").css({ "opacity": 1, "pointer-events": "auto"});
	},function(){
		$(this).siblings(".tooltip").css({ "opacity": 0, "pointer-events": "auto"});
	});
	*/
	//Upvote.create('runoobvote-id', {callback: vote_callback});
	var ajaxurl = 'https://www.runoob.com/wp-admin/admin-ajax.php';
	var callback = function(data) {
		//console.log($('#runoobvote-id').upvote('upvoted'));
		//console.log($('#runoobvote-id').upvote('downvoted'));
		//console.log(data);
		_vote_action = data.action;
		id_arr = data.id.split('-');
		um_id= id_arr[2];
		//console.log(um_id);
		
		var re = /^[1-9]+/;
		if (re.test(um_id)) { 
			var ajax_data = {
				_vote_action: _vote_action,
				action: "pinglun_zan",
				um_id: um_id,
				um_action: "ding"
			};
			//console.log(ajax_data);
			$.post(ajaxurl,ajax_data,function(status){
				//if(status.vote_num>999) {
				//	_voteHtml = '<span style="display: block; text-align: center;font-size: 20px; color: #6a737c; margin: 8px 0;">'+kFormatter(status.vote_num) +'</span>';
				//	$("#runoobvote-id-" + um_id + " .count").hide().after(_voteHtml);
				//}
				
			});
		}
	};
	if($('#comments').length && $('.upvotejs').length){
		$('.upvotejs').upvote({id: 7267, callback: callback});
	
		$.post(ajaxurl,{"action":"pinglun_zan","postid":7267},function(data){  
			$(data).each(function(key,value) {
				$("#runoobvote-id-" + value.commid + " .upvote").addClass(value.upvotejs_class);
				$("#runoobvote-id-" + value.commid + " .downvote").addClass(value.downvote_class);
				$("#runoobvote-id-" + value.commid + " .count").text(value.upvote_count);
			})
		},'json');
		
	}
	
	
});
function isBlank(str) {
    return (!str || /^\s*$/.test(str));
}
function kFormatter(num) {
	// return num;
    return Math.abs(num) > 999 ? Math.sign(num)*((Math.abs(num)/1000).toFixed(1)) + 'k' : Math.sign(num)*Math.abs(num)
}

</script>

<link rel="stylesheet" href="../0/qa.css?1.44">
<link rel="stylesheet" type="text/css" href="../0/simditor.min.css" />
<script type="text/javascript" src=""></script>
<script type="text/javascript" src=""></script>
<script type="text/javascript" src=""></script>
<script type="text/javascript" src=""></script>
<script type="text/javascript" src=""></script>
		<div class="sidebar-box ">
				

<style>	
.responsive_ad1 { display:none; }
@media(min-width: 800px) { .responsive_ad1 {  display:block;margin:0 auto;} }
</style>
<div id="ad-336280" >

<script async src=""
     crossorigin="anonymous"></script>
<!-- 移动版 自动调整 -->
<ins class="adsbygoogle"
     style="display:block"
     data-ad-client="ca-pub-5751451760833794"
     data-ad-slot="1691338467"
     data-ad-format="auto"
     data-full-width-responsive="true"></ins>
<script>
     (adsbygoogle = window.adsbygoogle || []).push({});
</script>
		</div>
				</div>
		
	</div>
</div>
	

<!-- 右边栏 -->
<div class="fivecol last right-column">

<style>
.sidebar-tree .double-li {
    width:300px;
}
.sidebar-tree .double-li li {
    width: 44%;
    line-height: 1.5em;
    border-bottom: 1px solid #ccc;
    float: left;
    display: inline;
}
</style>

    
        <div class="sidebar-box re-box re-box-large">
        <div class="sidebar-box recommend-here" style="margin: 0 auto;">
            <a href="javascript:void(0);" style="font-size: 16px; color:#64854c;font-weight:bold;"> <i class="fa fa-list" aria-hidden="true"></i> 分类导航</a>
        </div>
    <div class="sidebar-box sidebar-cate">
        
        <div class="sidebar-tree" >
            <ul><li style="margin: 0;"><a href="javascript:void(0);" class="tit"> HTML / CSS</a><ul class="double-li"><li><a title="HTML 教程" href="../html/html-tutorial.html">HTML 教程</a></li><li><a title="HTML5 教程" href="../html/html5-intro.html">HTML5 教程</a></li><li><a title="CSS 教程" href="../css/css-tutorial.html">CSS 教程</a></li><li><a title="CSS3 教程" href="../css3/css3-tutorial.html">CSS3 教程</a></li><li><a title="Bootstrap3 教程" href="../bootstrap/bootstrap-tutorial.html">Bootstrap3 教程</a></li><li><a title="Bootstrap4 教程" href="../bootstrap4/bootstrap4-tutorial.html">Bootstrap4 教程</a></li><li><a title="Bootstrap5 教程" href="../bootstrap5/bootstrap5-tutorial.html">Bootstrap5 教程</a></li><li><a title="Font Awesome 教程" href="../font-awesome/fontawesome-tutorial.html">Font Awesome 教程</a></li><li><a title="Foundation 教程" href="../foundation/foundation-tutorial.html">Foundation 教程</a></li></ul></li><li style="margin: 0;"><a href="javascript:void(0);" class="tit"> JavaScript</a><ul class="double-li"><li><a title="JavaScript 教程" href="../js/js-tutorial.html">JavaScript 教程</a></li><li><a title="HTML DOM 教程" href="../htmldom/htmldom-tutorial.html">HTML DOM 教程</a></li><li><a title="jQuery 教程" href="../jquery/jquery-tutorial.html">jQuery 教程</a></li><li><a title="AngularJS 教程" href="../angularjs/angularjs-tutorial.html">AngularJS 教程</a></li><li><a title="AngularJS2 教程" href="../angularjs2/angularjs2-tutorial.html">AngularJS2 教程</a></li><li><a title="Vue.js 教程" href="../vue2/vue-tutorial.html">Vue.js 教程</a></li><li><a title="Vue3 教程" href="../vue3/vue3-tutorial.html">Vue3 教程</a></li><li><a title="React 教程" href="../react/react-tutorial.html">React 教程</a></li><li><a title="TypeScript 教程" href="../typescript/ts-tutorial.html">TypeScript 教程</a></li><li><a title="jQuery UI 教程" href="../jqueryui/jqueryui-tutorial.html">jQuery UI 教程</a></li><li><a title="jQuery EasyUI 教程" href="../jeasyui/jqueryeasyui-tutorial.html">jQuery EasyUI 教程</a></li><li><a title="Node.js 教程" href="../nodejs/nodejs-tutorial.html">Node.js 教程</a></li><li><a title="AJAX 教程" href="../ajax/ajax-tutorial.html">AJAX 教程</a></li><li><a title="JSON 教程" href="../json/json-tutorial.html">JSON 教程</a></li><li><a title="Echarts 教程" href="../echarts/echarts-tutorial.html">Echarts 教程</a></li><li><a title="Chart.js 教程" href="../chartjs/chartjs-tutorial.html">Chart.js 教程</a></li><li><a title="Highcharts 教程" href="../highcharts/highcharts-tutorial.html">Highcharts 教程</a></li><li><a title="Google 地图 教程" href="../googleapi/google-maps-basic.html">Google 地图 教程</a></li></ul></li><li style="margin: 0;"><a href="javascript:void(0);" class="tit"> 服务端</a><ul class="double-li"><li><a title="Python 教程" href="../python3/python3-tutorial.html">Python 教程</a></li><li><a title="Python2.x 教程" href="../python/python-tutorial.html">Python2.x 教程</a></li><li><a title="Linux 教程" href="../linux/linux-tutorial.html">Linux 教程</a></li><li><a title="Docker 教程" href="../docker/docker-tutorial.html">Docker 教程</a></li><li><a title="Ruby 教程" href="../ruby/ruby-tutorial.html">Ruby 教程</a></li><li><a title="Java 教程" href="../java/java-tutorial.html">Java 教程</a></li><li><a title="C 教程" href="../c/c-tutorial.html">C 教程</a></li><li><a title="C++ 教程" href="../cplusplus/cpp-tutorial.html">C++ 教程</a></li><li><a title="Perl 教程" href="../perl/perl-tutorial.html">Perl 教程</a></li><li><a title="Servlet 教程" href="../servlet/servlet-tutorial.html">Servlet 教程</a></li><li><a title="JSP 教程" href="../jsp/jsp-tutorial.html">JSP 教程</a></li><li><a title="Lua 教程" href="../lua/lua-tutorial.html">Lua 教程</a></li><li><a title="Rust 教程" href="../rust/rust-tutorial.html">Rust 教程</a></li><li><a title="Scala 教程" href="../scala/scala-tutorial.html">Scala 教程</a></li><li><a title="Go 教程" href="../go/go-tutorial.html">Go 教程</a></li><li><a title="PHP 教程" href="../php/php-tutorial.html">PHP 教程</a></li><li><a title="数据结构与算法" href="../data-structures/data-structures-tutorial.html">数据结构与算法</a></li><li><a title="Django 教程" href="../django/django-tutorial.html">Django 教程</a></li><li><a title="Zookeeper 教程" href="../w3cnote/zookeeper-tutorial.html">Zookeeper 教程</a></li><li><a title="设计模式" href="../design-pattern/design-pattern-tutorial.html">设计模式</a></li><li><a title="正则表达式" href="../regexp/regexp-tutorial.html">正则表达式</a></li><li><a title="Maven 教程" href="../maven/maven-tutorial.html">Maven 教程</a></li><li><a title="Verilog 教程" href="../w3cnote/verilog-tutorial.html">Verilog 教程</a></li><li><a title="ASP 教程" href="../asp/asp-tutorial.html">ASP 教程</a></li><li><a title="AppML 教程" href="../appml/appml-tutorial.html">AppML 教程</a></li><li><a title="VBScript 教程" href="../vbscript/vbscript-tutorial.html">VBScript 教程</a></li></ul></li><li style="margin: 0;"><a href="javascript:void(0);" class="tit"> 数据库</a><ul class="double-li"><li><a title="SQL 教程" href="../sql/sql-tutorial.html">SQL 教程</a></li><li><a title="MySQL 教程" href="../mysql/mysql-tutorial.html">MySQL 教程</a></li><li><a title="PostgreSQL 教程" href="../postgresql/postgresql-tutorial.html">PostgreSQL 教程</a></li><li><a title="SQLite 教程" href="../sqlite/sqlite-tutorial.html">SQLite 教程</a></li><li><a title="MongoDB 教程" href="../mongodb/mongodb-tutorial.html">MongoDB 教程</a></li><li><a title="Redis 教程" href="../redis/redis-tutorial.html">Redis 教程</a></li><li><a title="Memcached 教程" href="../Memcached/Memcached-tutorial.html">Memcached 教程</a></li></ul></li><li style="margin: 0;"><a href="javascript:void(0);" class="tit"> 数据分析</a><ul class="double-li"><li><a title="Python 教程" href="../python3/python3-tutorial.html">Python 教程</a></li><li><a title="NumPy 教程" href="../numpy/numpy-tutorial.html">NumPy 教程</a></li><li><a title="Pandas 教程" href="../pandas/pandas-tutorial.html">Pandas 教程</a></li><li><a title="Matplotlib 教程" href="../matplotlib/matplotlib-tutorial.html">Matplotlib 教程</a></li><li><a title="Scipy 教程" href="../scipy/scipy-tutorial.html">Scipy 教程</a></li><li><a title="R 教程" href="../r/r-tutorial.html">R 教程</a></li><li><a title="Julia 教程" href="../julia/julia-tutorial.html">Julia 教程</a></li></ul></li><li style="margin: 0;"><a href="javascript:void(0);" class="tit"> 移动端</a><ul class="double-li"><li><a title="Android 教程" href="../w3cnote/android-tutorial-intro.html">Android 教程</a></li><li><a title="Swift 教程" href="../swift/swift-tutorial.html">Swift 教程</a></li><li><a title="jQuery Mobile 教程" href="../jquerymobile/jquerymobile-tutorial.html">jQuery Mobile 教程</a></li><li><a title="ionic 教程" href="../ionic/ionic-tutorial.html">ionic 教程</a></li><li><a title="Kotlin 教程" href="../kotlin/kotlin-tutorial.html">Kotlin 教程</a></li></ul></li><li style="margin: 0;"><a href="javascript:void(0);" class="tit"> XML 教程</a><ul class="double-li"><li><a title="XML 教程" href="../xml/xml-tutorial.html">XML 教程</a></li><li><a title="DTD 教程" href="../dtd/dtd-tutorial.html">DTD 教程</a></li><li><a title="XML DOM 教程" href="../dom/dom-tutorial.html">XML DOM 教程</a></li><li><a title="XSLT 教程" href="../xsl/xsl-tutorial.html">XSLT 教程</a></li><li><a title="XPath 教程" href="../xpath/xpath-tutorial.html">XPath 教程</a></li><li><a title="XQuery 教程" href="../xquery/xquery-tutorial.html">XQuery 教程</a></li><li><a title="XLink 教程" href="../xlink/xlink-tutorial.html">XLink 教程</a></li><li><a title="XPointer 教程" href="../xlink/xlink-tutorial.html">XPointer 教程</a></li><li><a title="XML Schema 教程" href="../schema/schema-tutorial.html">XML Schema 教程</a></li><li><a title="XSL-FO 教程" href="../xslfo/xslfo-tutorial.html">XSL-FO 教程</a></li><li><a title="SVG 教程" href="../svg/svg-tutorial.html">SVG 教程</a></li></ul></li><li style="margin: 0;"><a href="javascript:void(0);" class="tit"> ASP.NET</a><ul class="double-li"><li><a title="ASP.NET 教程" href="../aspnet/aspnet-tutorial.html">ASP.NET 教程</a></li><li><a title="C# 教程" href="../csharp/csharp-tutorial.html">C# 教程</a></li><li><a title="Web Pages 教程" href="../aspnet/webpages-intro.html">Web Pages 教程</a></li><li><a title="Razor 教程" href="../aspnet/razor-intro.html">Razor 教程</a></li><li><a title="MVC 教程" href="../aspnet/mvc-intro.html">MVC 教程</a></li><li><a title="Web Forms 教程" href="../aspnet/aspnet-intro.html">Web Forms 教程</a></li></ul></li><li style="margin: 0;"><a href="javascript:void(0);" class="tit"> Web Service</a><ul class="double-li"><li><a title="Web Service 教程" href="../webservices/webservices-tutorial.html">Web Service 教程</a></li><li><a title="WSDL 教程" href="../wsdl/wsdl-tutorial.html">WSDL 教程</a></li><li><a title="SOAP 教程" href="../soap/soap-tutorial.html">SOAP 教程</a></li><li><a title="RSS 教程" href="../rss/rss-tutorial.html">RSS 教程</a></li><li><a title="RDF 教程" href="../rdf/rdf-tutorial.html">RDF 教程</a></li></ul></li><li style="margin: 0;"><a href="javascript:void(0);" class="tit"> 开发工具</a><ul class="double-li"><li><a title="Eclipse 教程" href="../eclipse/eclipse-tutorial.html">Eclipse 教程</a></li><li><a title="Git 教程" href="../git/git-tutorial.html">Git 教程</a></li><li><a title="Svn 教程" href="../svn/svn-tutorial.html">Svn 教程</a></li><li><a title="Markdown 教程" href="../markdown/md-tutorial.html">Markdown 教程</a></li></ul></li><li style="margin: 0;"><a href="javascript:void(0);" class="tit"> 网站建设</a><ul class="double-li"><li><a title="HTTP 教程" href="../http/http-tutorial.html">HTTP 教程</a></li><li><a title="网站建设指南" href="../web/web-buildingprimer.html">网站建设指南</a></li><li><a title="浏览器信息" href="../browsers/browser-information.html">浏览器信息</a></li><li><a title="网站主机教程" href="../hosting/hosting-tutorial.html">网站主机教程</a></li><li><a title="TCP/IP 教程" href="../tcpip/tcpip-tutorial.html">TCP/IP 教程</a></li><li><a title="W3C 教程" href="../w3c/w3c-tutorial.html">W3C 教程</a></li><li><a title="网站品质" href="../quality/quality-tutorial.html">网站品质</a></li></ul></li></ul>            </div>
    
    </div>
    </div>
    <br>
    
    <div class="sidebar-box re-box re-box-large">
        <div class="sidebar-box recommend-here">
            <a href="javascript:void(0);">Advertisement</a>
        </div>
        <div class="re-600160" id="sidebar-right-re">
                <script async src=""></script>
        <!-- 侧栏1 -->
        <ins class="adsbygoogle"
             style="display:inline-block;width:160px;height:600px"
             data-ad-client="ca-pub-5751451760833794"
             data-ad-slot="4106274865"></ins>
        <script>
        (adsbygoogle = window.adsbygoogle || []).push({});
        </script>
                </div>
    </div>
</div></div>

</div>

<script>
var aid = 7267;
function coll() {
	$.post( '/wp-content/themes/runoob/option/user/userinfo.php', {aid:aid, action:"collarticle", opt:'add'},function( data ) {
		if(data.error==0) {
			$("#content").find("h1:first").find("a").attr("href","javascript:void(0);");
			$("#content").find("h1:first").find("img").attr("src","http://www.runoob.com/wp-content/themes/runoob/assets/img/coll2.png").css({width:32+"px",height:32+"px"});
		}
		alert(data.msg);
	},'json');
}
</script>


<!-- 反馈对话框开始 -->
<script src=""></script>
<link rel="stylesheet" href="../0/feedback.css?1.0" />
<script type="text/javascript">
$.feedback({
    ajaxURL: '/feedback/runoob_feedback.php',
	html2canvasURL: '/wp-content/themes/runoob/assets/feedback/stable/2.0/html2canvas.js',
	onClose: function () {
         window.location.reload();
    }
});
</script>
<!-- 反馈对话框结束 -->
<button class="feedback-btn feedback-btn-gray">反馈/建议</button>
<!-- 底部 -->
<div id="footer" class="mar-t50">
   <div class="runoob-block">
    <div class="runoob cf">
     <dl>
      <dt>
       在线实例
      </dt>
      <dd>
       &middot;<a target="_blank" href="../html/html-examples.html">HTML 实例</a>
      </dd>
      <dd>
       &middot;<a target="_blank" href="../css/css-examples.html">CSS 实例</a>
      </dd>
      <dd>
       &middot;<a target="_blank" href="../js/js-examples.html">JavaScript 实例</a>
      </dd>
      <dd>
       &middot;<a target="_blank" href="../ajx/ajax-examples.html">Ajax 实例</a>
      </dd>
       <dd>
       &middot;<a target="_blank" href="../jquery/jquery-examples.html">jQuery 实例</a>
      </dd>
      <dd>
       &middot;<a target="_blank" href="../xml/xml-examples.html">XML 实例</a>
      </dd>
      <dd>
       &middot;<a target="_blank" href="../java/java-examples.html">Java 实例</a>
      </dd>
     
     </dl>
     <dl>
      <dt>
      字符集&工具
      </dt>
      <dd>
       &middot; <a target="_blank" href="../charsets/html-charsets.html">HTML 字符集设置</a>
      </dd>
      <dd>
       &middot; <a target="_blank" href="../tags/html-ascii.html">HTML ASCII 字符集</a>
      </dd>
     <dd>
       &middot; <a target="_blank" href="https://c.runoob.com/front-end/6939/">JS 混淆/加密</a>
      </dd> 
      <dd>
       &middot; <a target="_blank" href="https://c.runoob.com/front-end/6232/">PNG/JPEG 图片压缩</a>
      </dd>
      <dd>
       &middot; <a target="_blank" href="../tags/html-colorpicker.html">HTML 拾色器</a>
      </dd>
      <dd>
       &middot; <a target="_blank" href="..//c.runoob.com/front-end/53">JSON 格式化工具</a>
      </dd>
      <dd>
       &middot; <a target="_blank" href="..//c.runoob.com/front-end/6680/">随机数生成器</a>
      </dd>
     </dl>
     <dl>
      <dt>
       最新更新
      </dt>
                   <dd>
       &middot;
      <a href="../matplotlib/matplotlib-imread.html" title="Matplotlib imread() 方法">Matplotlib imre...</a>
      </dd>
              <dd>
       &middot;
      <a href="../matplotlib/matplotlib-imsave.html" title="Matplotlib imsave() 方法">Matplotlib imsa...</a>
      </dd>
              <dd>
       &middot;
      <a href="../matplotlib/matplotlib-imshow.html" title="Matplotlib imshow() 方法">Matplotlib imsh...</a>
      </dd>
              <dd>
       &middot;
      <a href="../matplotlib/matplotlib-hist.html" title="Matplotlib 直方图">Matplotlib 直方图</a>
      </dd>
              <dd>
       &middot;
      <a href="../python3/python-func-object.html" title="Python object() 函数">Python object()...</a>
      </dd>
              <dd>
       &middot;
      <a href="../python3/python-ai-draw.html" title="Python AI 绘画">Python AI 绘画</a>
      </dd>
              <dd>
       &middot;
      <a href="../w3cnote/cursor-editor.html" title="神辅助 Cursor 编辑器，加入 GPT-4 让编码更轻松！">神辅助 Cursor ...</a>
      </dd>
             </dl>
     <dl>
      <dt>
       站点信息
      </dt>
      <dd>
       &middot;
       <a target="_blank" href="mailto:admin@runoob.com" rel="external nofollow">意见反馈</a>
       </dd>
      <dd>
       &middot;
      <a target="_blank" href="../disclaimer">免责声明</a>
       </dd>
      <dd>
       &middot;
       <a target="_blank" href="../aboutus">关于我们</a>
       </dd>
      <dd>
       &middot;
      <a target="_blank" href="../archives">文章归档</a>
      </dd>
    
     </dl>
    
     <div class="search-share">
      <div class="app-download">
        <div>
         <strong>关注微信</strong>
        </div>
      </div>
      <div class="share">
      <img width="128" height="128" src="/wp-content/themes/runoob/assets/images/qrcode.png" />
       </div>
     </div>
     
    </div>
   </div>
   <div class="w-1000 copyright">
     Copyright &copy; 2013-2023    <strong><a href="../" target="_blank">菜鸟教程</a></strong>&nbsp;
    <strong><a href="../" target="_blank">runoob.com</a></strong> All Rights Reserved. 备案号：<a target="_blank" rel="nofollow" href="https://beian.miit.gov.cn/">闽ICP备15012807号-1</a>
   </div>
  </div>
  <div class="fixed-btn">
    <a class="go-top" href="javascript:void(0)" title="返回顶部"> <i class="fa fa-angle-up"></i></a>
    <a class="qrcode"  href="javascript:void(0)" title="关注我们"><i class="fa fa-qrcode"></i></a>
    <a class="writer" style="display:none" href="javascript:void(0)"   title="标记/收藏"><i class="fa fa-star" aria-hidden="true"></i></a>
    <!-- qrcode modal -->
    <div id="bottom-qrcode" class="modal panel-modal hide fade in">
      <h4>微信关注</h4>
      <div class="panel-body"><img alt="微信关注" width="128" height="128" src="/wp-content/themes/runoob/assets/images/qrcode.png"></div> 
    </div>
  </div>

 <div style="display:none;">
<script async src="https://www.googletagmanager.com/gtag/js?id=UA-84264393-2"></script>
<script>
  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments);}
  gtag('js', new Date());

  gtag('config', 'UA-84264393-2');
</script>
<script>
var _hmt = _hmt || [];
(function() {
  var hm = document.createElement("script");
  hm.src = "https://hm.baidu.com/hm.js?3eec0b7da6548cf07db3bc477ea905ee";
  var s = document.getElementsByTagName("script")[0]; 
  s.parentNode.insertBefore(hm, s);
})();
</script>

</div>
<script>
window.jsui={
    www: 'https://www.runoob.com',
    uri: 'https://www.runoob.com/wp-content/themes/runoob'
};
</script>

<script src=""></script>
<script src=""></script>

</body>
</html>